From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx0b-00082601.pphosted.com ([67.231.153.30]:40416 "EHLO mx0b-00082601.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750735AbaETXgB (ORCPT ); Tue, 20 May 2014 19:36:01 -0400 Message-ID: <537BE73F.7040307@fb.com> Date: Tue, 20 May 2014 19:37:35 -0400 From: Chris Mason MIME-Version: 1.0 To: "H. Peter Anvin" , "linux-btrfs@vger.kernel.org" Subject: Re: Formalizing the use of Boot Area B References: <537403E3.6090902@zytor.com> <537BE54B.3060603@zytor.com> In-Reply-To: <537BE54B.3060603@zytor.com> Content-Type: text/plain; charset="UTF-8" Sender: linux-btrfs-owner@vger.kernel.org List-ID: On 05/20/2014 07:29 PM, H. Peter Anvin wrote: > On 05/14/2014 05:01 PM, H. Peter Anvin wrote: >> It turns out that the primary 64K "Boot Area A" is too small for some >> applications and/or some architectures. >> >> When I discussed this with Chris Mason, he pointed out that the area >> beyond the superblock is also unused, up until at least the megabyte >> point (from my reading of the mkfs code, it is actually slightly more >> than a megabyte.) >> >> This is present in all versions of mkfs.btrfs that has the superblock at >> 64K (some very early ones had the superblock at 16K, but that format is >> no longer supported), so all that is needed is formalizing the specs as >> to the use of this area. >> >> My suggestion is that 64-128K is reserved for extension of the >> superblock and/or any other filesystem uses, and 128-1024K is defined as >> Boot Area B. However, if there may be reason to reserve more, then we >> should do that. Hence requesting a formal decision as to the extent and >> ownership of this area. >> >> -hpa >> > > Ping on this? If I don't hear back on this I will probably just go > ahead and use 128K-1024K. Hi Peter, We do leave the first 1MB of each device alone. Can we do 256K-1024K for the boot loader? We don't have an immediate need for the extra space, but I'd like to reserve a little more than the extra 64KB. -chris